The invention relates to a timer clock for timing an operation such as oven cooking and for recording of the time of day, including means for adjustment and read-out which makes possible the selective adjustment of an unextendedly or extendedly shown switching-on period.
Such timer clocks or switch clocks are known per se. Thus, for example, a timer clock for ovens has been known, where an area of a scale, with an unextendedly shown switch-on time extends on a scale starting out from a zero point to one side, while starting out from the zero point toward the other side, a range of scale with an extendedly shown switch-on time extends. By an "unextended" time period is meant one which is marked in infrequent increments, such as hourly increments, while an "extended" time period refers to one which is marked at more frequent increments, such as one minute increments, for example. A separate area of scale with an extendedly shown time period of, for example, 5 to 10 minutes is required in case of this clock, because in an unextendedly shown range of the scale, which for example, comprises 2 hours, neither an exact reading nor a possibility of fine adjustment of only a few minutes is possible in the scale sector of the last minute. The user of a timer clock, however, wants to know exactly at the end of the cooking process, how long the cooking process should yet continue. He additionally also requires a possibility of exact adjustment for short cooking processes of a few minutes. Therefore, a separate range of the scale with an extendedly shown switch-on duration must be provided. A disadvantage of timer clocks of this type therefore is the impossibility of adjusting and reading, in the last section of the scale of the last minutes of the switch-on time of the unextended range of the scale, a precise duration of time. Another disadvantage lies in the operation of this timer, which forces the user to adjust either only a short but relatively precise switch-on time or to relinquish a precisely adjustable and readable switch-on time and instead the program in the area of the last minute of the switch-on time a precisely adjustable and readable switch-on time.
The drive for the adjusted switch-on takes place in that case, in connection with the extendedly shown switch-on time, via a first release clutch and a separate gear. The drive for the extendedly shown switch-on time takes place via a second separate release clutch and another gear. The drive of the time of day mechanism is accomplished separately via a third gear.
Therefore, the object of the invention is to create a simple and inexpensive timer clock, suitable for mass production, which makes possible a precise and reproduceable adjustment of the reading and switching even in the area of the last minute of an extended switching-on time, whereby the switch clock should be easily operable.